1. Field of Invention
The present invention relates to a semiconductor process and a composition for the same, and more particularly to an etching method and an etching composition.
2. Description of Related Art
As the demand for high-density memories such as floating gate memories, charge trapping memories, non-volatile memories or embedded memories is increased, the design of memory units is changed from a planar structure to a three-dimensional structure, so as to increase the storage capacity in a limited chip area.
In a three-dimensional structure, in order to achieve a higher storage capacity, the number of layers of stacks is increased, and the aspect ratio during an etching is accordingly enhanced. However, the reaching depths of ions used in an etching step such as an anisotropic etching are limited, so that incomplete etching is easily observed, and stepped residues may remain at the bottom of the trench. In such case, the formed device may be turned on abnormally due to the undesired residues, and short current may be generated.